text: /*
   * HCOM demuxer
   * Copyright (c) 2019 Paul B Mahol
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "libavutil/intreadwrite.h"
  #include "libavcodec/internal.h"
  #include "avformat.h"
  #include "internal.h"
  #include "pcm.h"
  
  static int hcom_probe(const AVProbeData *p)
  {
      if (p->buf_size < 132)
          return 0;
      if (!memcmp(p->buf+65, "FSSD", 4) &&
          !memcmp(p->buf+128, "HCOM", 4))
          return AVPROBE_SCORE_MAX;
      return 0;
  }
  
  static int hcom_read_header(AVFormatContext *s)
  {
      AVStream *st;
      av_unused unsigned data_size, rsrc_size, huffcount;
      unsigned compresstype, divisor;
      unsigned dict_entries;
      int ret;
  
      avio_skip(s->pb, 83);
      data_size = avio_rb32(s->pb);
      rsrc_size = avio_rb32(s->pb);
      avio_skip(s->pb, 128-91+4);
      huffcount = avio_rb32(s->pb);
      avio_skip(s->pb, 4);
      compresstype = avio_rb32(s->pb);
      if (compresstype > 1)
          return AVERROR_INVALIDDATA;
      divisor = avio_rb32(s->pb);
      if (divisor == 0 || divisor > 4)
          return AVERROR_INVALIDDATA;
      dict_entries = avio_rb16(s->pb);
  
      st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
  
      st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
      st->codecpar->channels    = 1;
      st->codecpar->sample_rate = 22050 / divisor;
      st->codecpar->codec_id    = AV_CODEC_ID_HCOM;
      st->codecpar->bits_per_coded_sample = 8;
      st->codecpar->block_align = 4;
  
      ret = ff_alloc_extradata(st->codecpar, dict_entries * 4 + 7);
      if (ret < 0)
          return ret;
      AV_WB16(st->codecpar->extradata, dict_entries);
      AV_WB32(st->codecpar->extradata + 2, compresstype);
      avio_read(s->pb, st->codecpar->extradata + 6, dict_entries * 4);
      avio_skip(s->pb, 1);
      st->codecpar->extradata[dict_entries * 4 + 6] = avio_r8(s->pb);
  
      avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
  
      return 0;
  }
  
  const AVInputFormat ff_hcom_demuxer = {
      .name           = "hcom",
      .long_name      = NULL_IF_CONFIG_SMALL("Macintosh HCOM"),
      .read_probe     = hcom_probe,
      .read_header    = hcom_read_header,
      .read_packet    = ff_pcm_read_packet,
  };
  